Acylated anthocyanins from red radish (Raphanus sativus L.)

Twelve acylated anthocyanins were isolated from the red radish (Raphanus sativus L.) and their structures were determined by spectroscopic analyses. Six of these were identified as pelargonidin 3-O-[6-O-(E)-feruloyl-2-O-beta-D-glucopyranosyl]-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-caffeoyl-2-O-(6-(E)-feruloyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-p-coumaroyl-2-O-(6-(E)-caffeoyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-feruloyl-2-O-(6-(E)-caffeoyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-p-coumaroyl-2-O-(6-(E)-feruloyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), and pelargonidin 3-O-[6-O-(E)-feruloyl-2-O-(2-(E)-feruloyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside).     

Interrelationship between chromocentres and chiasmata in radish (Raphanus sativus L.)

A comparative study of the number and distribution of chromocentres in interphase nuclei and mean chiasma frequency at diakinesis has been made in three varietal populations of radish (Raphanus sativus L.), Scarlet Globe, Japanese White and Chinese White. The study showed a significant difference between the varietal populations in mean chiasma frequency and number of chromocentres (P<0.001), indicating that these nuclear characters are genotypically controlled. The correlation analysis revealed a significant negative correlation between chromocentres and chiasma frequency (r= -0.87). It was concluded that an increase in the amount of constitutive heterochromatin, as inferred by chromocentre counts, adversely affects the chiasma frequency and, consequently, genetic recombination in radish.     

QTL mapping of clubroot resistance in radish (Raphanus sativus L.)

A QTL analysis for clubroot resistance (CR) of radish was performed using an F₂ population derived from a crossing of a CR Japanese radish and a clubroot-susceptible (CS) Chinese radish. F₃ plants obtained by selfing of F₂ plants were used for the CR tests. The potted seedlings were inoculated and the symptom was evaluated 6 weeks thereafter. The mean disease indexes of the F₃ plants were used for the phenotype of the F₂. The results of two CR tests were analyzed for the presence of QTL. A linkage map was constructed using AFLP and SSR markers; it spanned 554 cM and contained 18 linkage groups. A CR locus was observed in the top region of linkage group 1 in two tests. Therefore, the present results suggest that a large part of radish CR is controlled by a single gene or closely linked genes in this radish population, although minor effects of other genomic areas cannot be ruled out. The CR locus was named Crs1. Markers linked to Crs1 showed sequence homology to the genomic region of the top of chromosome 3 of Arabidopsis, as in the case of Crr3, a CR locus in Brassica rapa. These markers should be useful for breeding CR cultivars of radish. As Japanese radishes are known to be highly resistant or immune to clubroot, these markers may also be useful in the introgression of this CR gene to Brassica crops.     

Polyamines as antioxidant protectors against paraquat damage in radish (Raphanus sativus L.) cotyledons

Pretreatment of radish cotyledons with polyamines (PAs; especially 1 mM spermidine) significantly improved their tolerance to subsequent 50 μM paraquat (PQ)-induced oxidative damage. Symptoms in the cotyledons, e.g., large accumulations of H₂O₂, and losses of fresh weight, chlorophyll, and proteins, were remarkably alleviated. Likewise, analysis of several enzymes belonging to the Superoxide dismutase (SOD)/ascorbate-glutathione cycle showed that pretreatment with PAs prevented typical PQ-induced declines in the total activities of SOD, ascorbate peroxidase (APX), and glutathione reductase (GR). Dehydroascorbate reductase (DHAR) activity, which normally decreases sharply under prolonged PQ exposure, was also highly maintained by PA treatment. In a native gel assay, two SOD isozymes (FeSOD and Cu/ZnSODI), two APX isozymes (APX1 and APX2), and two GSSG-specific isozymes (GR1 and GR2) proved to be more responsible for PQ tolerance, as manifested by the strong increases in their activities by spermidine (Spd) pretreatment. In addition, experiments with protein synthesis inhibitors (actinomycin D and cycloheximide) indicated that Spd could stimulatede novo synthesis of SOD and APX at the translational level. We can conclude that PAs may function as antioxidant protectors by invoking an efficient SOD/ascorbate-glutathione cycle in radish cotyledons exposed to PQ.     

Management of Alternaria blight of radish seed crop (Raphanus sativus L.)

Radish (Raphanus sativus L. var. Tasaki Mula) was used in this investigation. On foliar spray, among the three fungicides (Iprodione, Mancozeb and Carbendazim), Iprodione (0.25%) followed by Mancozeb (0.3%) provided the maximum control of Alternaria blight and increased seed yield during the first cropping season (2004–2005). The results in second cropping season (2005–2006), 10 December (early) transplanting with three sprays of Iprodione resulted lowest leaf area diseased, whereas plants in 25 December (normal) transplanting had the lower pod area diseased. In third cropping season (2006–2007), 25 October transplantation with BAU-Biofungicide (2.0%) and Iprodione (0.25%) foliar application showed significant effect in reducing Alternaria blight and increased seed yield by 120.45% and 97.73%, respectively over non-sprayed control. Bio-Biofungicide ranked second in reducing the disease, but ranked first in increasing seed yield. The cost benefit analysis of management practices for radish seed crop during 2005–2006 revealed that stickling transplanting in 25 December (normal) with two sprays of Iprodione (0.25%) yielded the highest return (BCR 3.27), whereas negative result (BCR ? 0.89) has been estimated in case of non-sprayed control plots in late transplanting (10 January). However, cost benefit analysis of cropping season 2006–2007 revealed that BAU-Biofungicide (2.0%) six sprays yielded the highest return (BCR 4.41) followed by six sprays of Iprodione (BCR 3.90). Finally, it may be concluded that Integration of early transplanting (25 October) with foliar sprays ofBAU-Biofungicide (2.0%) was found best for eco-friendly management of Alternaria blight of radish seed crop with significantly higher seed yield.     

Meta-topolin enhances regeneration and Agrobacterium-mediated genetic transformation in radish (Raphanus sativus L.)

In Vitro Cellular & Developmental Biology - Plant - Meta-topolin (mT) is a novel aromatic cytokinin that stimulates morphogenesis and is an alternative source of cytokinins frequently employed...     

Somatic embryogenesis and plant regeneration in tissue cultures of radish (Raphanus sativus L.)

Hypocotyl segments of 2- to 3-week-old radish (Raphanus sativus L. cv. F₁ Handsome Fall) seedlings produced yellowish compact calli when cultured on Murashige and Skoog's (MS) medium supplemented with 1 mgl^-1 2,4-dichlorophenoxyacetic acid (2,4-D). Upon transfer onto medium containing 6-benzyladenine and -naphthaleneacetic acid, up to 5.3% of the calli gave rise to a few somatic embryos. When subcultured for 3 to 6 months, 7% of the yellowish, compact calli produced white, compact calli which formed numerous embryos. These calli maintained their embryogenic capacity for over 18 months. When cultured on medium containing 0.1 to 3 mgl^-1 2,4-D, up to 90% of longitudinally sliced somatic embryo halves produced calli with numerous secondary embryos. Embryos were transferred onto medium containing 0.1 mgl^-1 2,4-D and 1 mgl^-1 abscisic acid where they developed into the cotyledonary stage. Upon transfer onto half-strength MS basal medium, approximately 90% of the embryos developed into plantlets. These plantlets were successfully transplanted in potting soil and after cold treatment they were grown to maturity in a phytotron.Abbreviation 2,4-D 2,4-dichlorophenoxyacetic acid - BA 6-benzyladenine - GA₃ gibberellin A₃ - IAA indole-3-acetic acid - MS Murashige and Skoog - NAA -naphthaleneacetic acid     

竹叶对萝卜幼苗生长的影响

采用琼脂混粉法研究了22属83种竹叶对萝卜幼苗生长的影响,结果表明:在2g·L^-1的添加浓度下,供试竹叶对萝卜幼苗表现出不同程度的抑制作用,且对根生长的抑制作用大于对胚轴生长和鲜重的抑制作用。刚竹属、簕竹属、大明竹属、牡竹属中,对根长的抑制率在50%以上的竹种分别占70.83%、71.43%、62.50%、85.71%;其它竹属的30种竹叶,有73.33%的竹种对萝卜幼苗根长的抑制率超过50%。淡竹、桂竹、孝顺竹、宜兴苦竹、长叶苦竹、甜龙竹、铺地竹和铁竹等8种竹叶对萝卜幼苗的抑制作用显著,对萝卜根的抑制率均在80%以上。结果对于竹类植物化感作用研究具有参考作用,对拓展竹叶资源的化学利用途径具有一定的指导意义。     

萝卜CMS不育系与保持系小孢子发生的细胞学研究

研究了萝卜胞质雄性不育系A2、A4及其相应保持系B2、B4的小孢子发生与花药壁发育的细胞学特征.结果表明,不育系A2的绒毡层细胞在四分体时期出现异常,小液泡增多,至单核期汇合形成大液泡,绒毡层细胞异常膨大;小孢子外壁染色浅,细胞壁受到破坏,最后与绒毡层一同降解.不育系A4在减数分裂期即表现出异常,绒毡层异常肥大;花药发育后期,小孢子外壁亦染色较浅;绒毡层细胞融合形成细胞团块侵入药室挤压小孢子,两者一同降解.     

Efficient Agrobacterium-mediated genetic transformation method using hypocotyl explants of radish (Raphanus sativus L.)

To investigate the gene function of radish (Raphanus sativus L.), several attempts have been made to generate genetically transformed radish. However, no efficient and relatively simple method for the genetic transformation of radish has been developed to date. In this study, we established an Agrobacterium-mediated genetic transformation method using the hypocotyl-derived explants of radish cultivar “Pirabikku”. Primarily based on the Brassica transformation procedure, we optimized it for radish transformation. Using this system, the transformation efficiency of radish hypocotyl explants by Agrobacterium tumefaciens strain GV3101 harboring pIG121-Hm was 13.3%. The copy number of transfer DNA integrated into the genome was either one or two in the four independent transgenic plants. Two of the four plants exhibited male sterility and did not produce self-pollinated seeds. Examination of the expression of the β-glucuronidase (GUS) gene in T₁ plants from fertile T₀ plants showed that the GUS genes were inherited. The improvement in the genetic transformation in this study might pave the way for accelerated molecular breeding and genetic analysis of radish.     

Thiocyanate content in relation to the quality features of radish Raphanus sativus L

Relationships between radish thiocyanate content and its dry weight, the content of sugar, protein, fibre, ascorbic acid, some minerals, the incidence of plant shooting, the firmness and pithiness of storage-roots, and the ratio of leaves to storageroot (wt/wt) were investigated. The analysis of linear correlation was based on numerous data from the 4-year field experiment with six radish cultivars and different sowing and harvest dates. The content of thiocyanate in radish roots was found to be positively correlated with their dry weight, and the content of total protein, crude fibre, and soluble sugar. A strong relationship was found between the content of thiocyanate and dry weight of radish leaves. The negative correlation between the thiocyanate content in the leaves and the firmness of storageroots and the positive correlation with their pithiness might indicate the translocation of this compounds into green plant parts during the ageing of root tissue. The root thiocyanate content and the percentage of shooting correlated significantly only in the case of Tokinashi. The closeness of relations between the ratio of leaves/storage-root and thiocyanate content, though in general small, was affected also by a cultivar. A similar effect was observed for the correlations between the thiocyanate contents in leaves and storage-roots.     

Subcellular localization and possible functions of gamma-glutamyltransferase in the radish (Raphanus sativus L.) plant

Previously we reported the purification of soluble gamma-glutamyltransferases (GGTs) from radish cotyledon. Subcellular fractionation of radish cells revealed that soluble GGT is a vacuolar enzyme. Acivicin, a GGT inhibitor, mediated the in vivo catabolism inhibition of the glutathione S-conjugate generated from endogenous glutathione and exogenously supplied monochlorobimane. Thus soluble GGT is possibly involved in the catabolism of glutathione S-conjugates.     

Effects of ageing on peroxidase activity and localization in radish (Raphanus sativus L.) seeds

Peroxidase activity was assayed in crude extracts of integument, cotyledons and embryo axis of radish seeds, deteriorated under accelerated ageing conditions. Over five days of ageing, in which germination decreased from 100 to 52%, the enzyme activity in integument was higher than that in other seed parts, increasing in the first days of ageing and then decreasing sharply in extremely aged seeds. Polyacrylamide gel electrophoresis analysis showed four peroxidase isoenzymes with MM of 98, 52.5, 32.8 and 29.5 kDa in the embryo axis of unaged seeds, and only the 32.8 and 29.5 kDa MM isoforms in the integument and cotyledons. In these parts of the seed, only the 29.5 kDa MM isoenzyme increased in activity in early days of ageing and decreased there-after. In the embryo axis, the 29.5 kDa MM isoenzyme activity increased slowly in the first day of ageing, while the 98 and 52.5 kDa MM isoenzyme activities disappeared. A cytochemical localization of peroxidase activity in the various tissues showed that main differences between unaged and extremely aged seeds occurred in the embryo axis.     

萝卜种质资源亲缘关系的RAPD分析

利用筛选出的12个随机引物,对来源于不同国家和地区的有代表性的56份萝卜种质资源遗传多样性进行了RAPD分析,共扩增出109条带,其中多态性带为72条,多态性带百分率为62.9%,种质平均期望杂合度为0.289.系统聚类分析将供试材料分为2大类、9组,主坐标分析将其分为3大类、7组,两种分类方法结果基本一致,后者能更为直观和清楚地反映群体之间的关系.     

The role of malate in ammonia assimilation in cotyledons of radish (Raphanus sativus L.)

The relationships between the metabolism of malate, nitrogen assimilation and biosynthesis of amino acids in response to different nitrogen sources (nitrate and ammonium) have been examined in cotyledons of radish (Raphanus sativus L.). Measurements of the activities of some key enzymes and pulse-chase experiments with [¹⁴C]malate indicate the operation of an anaplerotic pathway for malate, which is involved in the synthesis of glutamine during increased ammonia assimilation. It is most likely that the tricarboxylicacid cycle is supplied with carbon through entry of malate, formed via the phosphoenolpyruvate (PEP)-carboxylation pathway, when 2-oxoglutarate leaves the cycle to serve as precursor for an increased synthesis of glutamine via glutamate. This might occur predominantly in the cytosol via the activity of the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle, the NADH-dependent GOGAT being the rate-limiting activity.Abbreviations DTT dithiothreitol - EDTA ethylenediamine-tetraacetic acid - GDH glutamate dehydrogenase - GOGAT glutamate synthase (glutamine: 2-oxoglutarate aminotransferase) - GOT aspartate aminotransferase (glutamate: oxaloacetate transaminase) - GS glutamine synthetase - HPLC high-performance liquid chromatography - MCF extraction medium of methanol: chloroform: 7M formic acid, 12:5:3, by vol. - MDH malate dehydrogenase - MSO L-methionine, sulfoximine - PEPCase phosphoenolpyruvate carboxylase - TLC thin-layer chromatography